Gas turbine engines with multiple turbine stages include interstage seal arrangements between adjacent stages for improved operating efficiency. The interstage seal arrangements confine the flow of hot combustion core gases within an annular path around and between stationary turbine stator blades, nozzles, and also around and between adjacent rotor blades.
The interstage seal arrangements may also serve to confine and direct cooling air to cool the turbine disks, the turbine blade roots, and also the interior of the rotor blades themselves as rotor blade cooling facilities higher turbine inlet temperatures, which results in higher thermal efficiency of the engine and higher thrust output. The interstage seal configurations must also accommodate axial and radial movements of the turbine stage elements during engine operation as the several elements are subjected to a range of different loadings and different rates of expansion based upon local part temperatures and aircraft operating conditions.
One such interstage seal includes a monolithic interstage seal structure that spans the axial gap between the rotor disks. Although effective, the monolithic interstage seal is typically manufactured from high strength materials to withstand the relatively high hoop stresses induced by rotation. This may result in a relatively heavy seal structure that imposes additional weight adjacent the rotor disks. Another interstage seal is a segmented seal assembly in which multiple segments are assembled together circumferentially. Although effective, the multiple segments may increase transient load variation between the rotor disks and may result in additional leakage paths between the segments.